[Delphinus]

I think I saw my fairy wrasse bury himself in the sand, only a handful of times. (Like, maybe only 3 or 4 times.) Most of the time I'd find him wedged into a crevasse in the rock somewhere so I guess, at the least the species I had, is flexible in the bedding-down choices.

When I had scooter blenny/dragonets I noticed they would bury themselves in the sand, to sleep. You'd just see an eyeball sticking out of the sand and that's it.

But my psychedelic mandarin, he just finds a spot to settle down, and turns off his colour, and that's it. He'll be just there on top of the sand, perfectly asleep. I've never noticed if he's buried himself into sand.

Anyhow hope this random rambling is of some help.

I myself can't seem to tear myself away from the idea of a sandbed. Not yet, anyhow. I did put only a fraction of sand into my 90g from the defunct 72g, and I put rock down first so there's only sand in the open areas and none under the rocks (unless there's an opening in the rock that sort of allows it). I see worm tracks and tunnels and such in the 1" of sand I did put in .... so I have to believe that something is using the sand, and that something benefits the tank by adding to the overall biodiversity .... but other than that I can't really add too much quantification.